Implantable pump connector for catheter attachment

ABSTRACT

A catheter system for locking a catheter to an implantable pump and for effectively flushing a catheter after implantation within a body. A locking component comprises an extension boot and catheter lock that together fluidly connect the catheter to the pump in a secure, safe and effective manner. A catheter component comprises a design having kink-resistant walls and a unique tip. A flushing component comprises a hub and stylet combination characterized by a hydrophilic coating on the stylet and a flush through hub to allow flushing of the stylet while inside the catheter.

This application is a Divisional of U.S. Ser. No. 10/180,708 filed onJun. 26, 2002, the disclosure of which is incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to a catheter system and more particularlyto a catheter flushing and locking system for use with an implantablepump.

BACKGROUND OF THE INVENTION

Use of implantable pumps for treating chronic pain conditions has becomewidely accepted practice when more conservative means of relieving painhave failed. Implantable pump technology can be divided into two primarycategories, namely constant flow and programmable. Both technologiesincorporate an indwelling catheter to establish a fluid path from a pumpdisposed subcutaneously to a desired anatomical site, including but notlimited to, arterial or venous locations, the epidural space and theintrathecal space of the spine. Some of the reported complications withimplanted pumps deal with the connection between the pump and thecatheter, including leaks, disconnect and reduced flow. Other reportedcomplications involve the catheter itself, which include but are notlimited to, kinking, occlusion, disconnect, malposition, migration andreduced flow. Thus, the success of an implanted pump system is dependentin large part on a successful and dependable connection between the pumpand the catheter as well as the design of the catheter and theintroduction techniques utilized.

Prior art implantable pumps employ relatively tedious and oftencomplicated means for attaching the catheter to the pump, which also maypromote problems for the entire pump and catheter system. For example,screw driven clamping connections are both complicated and unreliable asthe required clamping action on the outer diameter of an unsupportedcatheter increases the risk of collapsing the inner lumen of thecatheter. Stent based designs that do utilize internal support solve theproblem of internal collapse, but require the additional step ofattachment involving multiple sutures around the connection area. Thesuturing process, as well as the sutures themselves, can lead to brokenor severed catheters at the suture site where the suture cuts throughthe catheter or surrounding support members. Also, variability in suturetying and force applied by the user leads to variability in attachment.Thus, a prior art approach to attaching the catheter to the pump hasbeen to utilize a barbed stem connector. The pump is fit with a barbedor flared outer stem for the catheter to be placed therearound. Theproblem with these designs, which are common in subcutaneous accessports, is a connection that is relatively unsecured and potential damageto the catheter caused by the barbed section. Another related problem isthat it is often difficult to ascertain whether a positive connectionbetween the pump and catheter has been established. This can lead tocatheter and/or pump damage as undue force is placed on the attachmentsystem in order to get verification of the connection.

In addition to these drawbacks of the prior art systems, one of theprimary concerns to overcome in developing a successful and reliableattachment system is that the catheters are generally very small indiameter while the pumps to which they are connected are relativelylarge. Thus, it is often physically difficult to make the connectionbetween the pump and the catheter.

Accordingly, it is an object of the present invention, in a systeminvolving an implantable pump and catheter, to provide a catheter systemfor use with implantable pumps and other known catheter-based systemsthat will maintain the effectiveness and longevity of the connection andsystem following implantation thereof.

It is also an object of the present invention to provide a connectionbetween the catheter and the pump which eliminates the need for suturingaround the catheter, avoids potential collapse of the catheter or otherattendant damage thereto.

It is a further object of the present invention to provide a connectionsystem for an implantable pump and catheter that overcomes thedifficulty arising from the size difference between the catheter andpump.

It is yet a further object of the present invention to provide aflexible interface between the catheter and pump body to facilitateattachment of the catheter and minimize strains on the connection.

It is still a further object of the present invention to provide aconnection system for an implantable pump and catheter, which is veryeasy and quick to implement.

It is also an object of the present invention to provide a connectionsystem for an implantable pump and catheter that confirms a secureconnection.

It is another object of the present invention to provide a connectionsystem for an implantable pump and catheter that is reliable andlong-lasting.

It is yet another object of the present invention to provide a catheterwith minimal contained dead space at the tip to minimize possiblecomplications from static fluid in the system.

It is still another object of the present invention to provide astiffening stylet to facilitate positioning of the catheter that is easyto remove and minimizes bunching and displacement of the catheter tipduring removal of the stylet.

Further objects and advantages of the present invention will becomeapparent from the ensuing description and drawings.

BRIEF SUMMARY OF THE INVENTION

In accordance with the present invention, a catheter system for lockinga catheter to an implantable pump and for effectively flushing acatheter after implantation within a body is provided. A lockingcomponent comprises an extension boot and catheter lock that togetherfluidly connect the catheter to the pump in a secure, safe and effectivemanner. A catheter component comprises a design having kink-resistantwalls and a unique tip. A flushing component comprises a hub and styletcombination characterized by a hydrophilic coating on the stylet and aflush through hub to allow flushing of the stylet while inside thecatheter.

What is claimed is a connection device for attaching a catheter to animplantable port or pump, wherein the catheter is in fluid communicationwith said port or pump, comprising a coupling device extending from saidport or pump, comprising an arm portion and a stem, wherein the shape ofthe arm portion is substantially similar to an outer contour of saidport or pump, and wherein the stem comprises a base portion and a tipportion and a locking device slideable along a length of the catheter,comprising varying diameter portions that communicate directly withdiameters of the base portion and tip portion of the stem, wherein alocking connection is established therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an implantable pump with attached bootand stem according to the present invention.

FIG. 2 is a side view of the boot and stem according to the presentinvention.

FIG. 3 is an enlarged view of the stem in FIG. 2.

FIG. 4 is a longitudinal cross-sectional view of a catheter lockaccording to the present invention.

FIG. 5 is an end view of the catheter lock in FIG. 4.

FIG. 6 is a side view of a catheter and flushing hub of the presentinvention.

FIG. 7 is a side view of a hub and stylet of the present invention.

FIG. 8 is perspective view of the hub, stylet and catheter of FIGS. 6and 7.

FIG. 9 is a cross-sectional view of the hub and stylet of FIG. 7.

FIG. 10 is a cut away view of a distal end of a catheter of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description illustrates the invention by way ofexample, not by way of limitation of the principles of the invention.This description will clearly enable one skilled in the art to make anduse the invention, and describes several embodiments, adaptations,variations, alternatives and uses of the invention, including what wepresently believe is the best mode of carrying out the invention.

The present invention is directed to a novel attachment device forsecurely connecting a catheter to a pump, which can be used in a varietyof applications to optimize efficiency and effectiveness. The presentinvention is also directed to a unique catheter configuration, alongwith means for introduction and positioning thereof within the body,which offers several advantages over prior art catheters and introducingsystems and can be used in various applications.

One example of a suitable pump for use with the present invention can beseen in FIG. 1 as implantable pump 10. Implantable pump 10 could be anymedical device that is implanted subcutaneously to deliver a steadystream of drugs or other fluids to the body. Generally, the implantedmedical device will contain a septum through which an inner chamber tohold and dispense the drug or fluid can be accessed via a needle. Themedical device will also have some type of mechanism to release the drugor fluid at predetermined intervals or in a steady stream at a givenflow rate. This timed interval or flow rate can be regulated viamechanism within the medical device or outside of the body using otherknown means.

Examples of implantable medical devices that would be suitable for usein conjunction with the present invention can be found in U.S.application Ser. No. 09/481,298, filed Jan. 11, 2000, entitled“Implantable refillable infusion device and septum replacement kit” andin U.S. Pat. No. 6,287,293, entitled “Method and apparatus for locatingthe injection point of an implanted medical device;” 6,213,973, entitled“Vascular access port with elongated septum;” 6,086,555, entitled “Dualreservoir vascular access port with two-piece housing and compoundseptum;” 5,833,654, entitled “Longitudinally aligned dual reservoiraccess port;” 5,049,141, entitled “Programmable valve pump;” and4,838,887, entitled “Programmable valve pump,” all of which areincorporated by reference herein.

The implantable pump 10 is shown in FIG. 1 with an inventive boot 20containing a stem 30 according to the present invention, which is shownin more detail in FIGS. 2 and 3. The boot 20 has an arm 24 that iscurved to conform to the outside of the pump 10 so that the overallprofile thereof is minimized to facilitate implantation andcompatibility within the body. While the boot 20 is shown as curved toconform to the shape of the pump 10, in an alternate embodiment a bootwould take on any shape of the outer contour of a port or pump torealize the advantages mentioned above. The boot 20 attaches to theimplantable pump 10 via connector tube 22, which has a lumen 26 thatfluidly connects the inner chambers of the implantable pump 10 (notshown) with the stem outlet 38. Of course, the boot 20 can be adaptedfurther to connect to various shapes and sizes of pumps other thanimplantable pump 10. For instance, in the case of a conventional portwith a straight stem, the boot 20 could be fashioned to replace thestraight stem to reduce port profile, or in the case of a dual portsystem, the boot could likewise be fashioned to accommodate the shape ofthe housing to reduce the overall space occupied by the port or pump.

Among the many advantages of the conformal shape of the boot are lesstissue trauma and reduced force on the catheter and catheter interfacewith the port or pump (i.e. a stem). Also, in a preferred embodiment ofthe present invention, the boot is made of a flexible material (such assilicone or a compliant polymer) so that it can be pulled away from theport or pump to which it is attached. This is important because in manyapplications, the catheters are extremely small, meaning that aphysician or medical technician can often find it very difficult to pushthe catheter onto a stem extending from the port or pump. By providing aflexible boot, the physician or medical technician can pull the bootaway from the port or pump, thereby facilitating attachment of thecatheter to the stem. After the catheter is sufficiently attached andthe boot is released, it will snap back into place, conforming onceagain to the shape of the port or pump.

In a preferred embodiment of the present invention, the stem 30 containsa base portion 32 and a tip portion 34. As shown in more detail in FIG.3, the base portion 32 includes a forward portion 36 and an engaginglock portion 33. The engaging lock portion 33 is shown as a largerdiameter in a wing configuration near a connecting portion 35 thatattaches to the arm 24 of the boot 20. The engaging lock portion 33 isconfigured to communicate with the geometry of a locking mechanism (seeFIG. 4) to secure the catheter 120 to the boot 20. Of course, theengaging lock portion 33 can take on various shapes and sizes and is notconfined to the embodiment shown. Indeed, other types of engagingdevices could be employed that would certainly be within the scope ofthe present invention, including twist locks, spring locks, etc.

The tip 34 is configured to receive the catheter 120 such that the lumen122 of the catheter 120 fits over the tip 34 and is expanded by a tipend 39. Depending on the size of the catheter 120, the size of the tip34 can vary, but generally, the diameter of a main body 37 of the tip 34will be slightly larger than the lumen of the catheter so that a tightfriction fit between the two is realized. In addition to the frictionfit between the main body 37 of the tip 34 and the catheter 120, tip end39 has a conical shape with a base portion attached to the main body 37to further ensure a tight fit between the catheter 120 and the tip 34.The diameter of the base portion of the tip end 39 is larger than thediameter of the main body 37 to make disengagement difficult, but not solarge that undue stress and resultant damage occurs to the catheter 120as a result of compression to the wall thereof. The tip end 39 can alsotake on different forms other than the conical shape shown that willpermit the catheter 120 to slide onto the stem 34, while ensuring thatsliding off of the stem is unlikely.

Referring now to FIGS. 4 and 5, a catheter lock 40 is shown. FIG. 4illustrates a longitudinal cross-sectional view of the catheter lock 40,which in the preferred embodiment is made of a hard shell construction(for example, polyacetal resin, polycarbonate or polysulfones) topositively fit over the catheter 120 to secure in place and provide anaudible and tactile lock and to provide added security againstinadvertent needle sticks. FIG. 5 shows an end view of the catheter lock40 from the locking end thereof, which is the end that engages with thebase portion 32 of the stem 30. Not shown in either view is an optionalradiopaque feature, which can be a metal ring, ink or other material onthe distal end of the catheter lock 40, providing easy visualizationunder x-ray or fluoroscopy to verify lock engagement and position. Ofcourse, a radiopaque section could be added to many different portionsof the catheter lock 40 for accomplishing the same objective. Thecatheter lock of the present invention provides an easy, one-stepconnection mechanism to secure a catheter to an extension of a port orpump, eliminating the need for cumbersome suturing, which may causedamage to the catheter and/or the connection. While a preferredembodiment of the catheter lock is described herein, it should beappreciated that many configurations are possible that would certainlybe within the scope of the present invention.

Referring again to FIGS. 4 and 5, the catheter lock 40 has five distinctdiameter portions each having a particular function with respect to thelocking of the catheter 120 to the stem 30. A middle portion 42 of thecatheter lock 40 contains the smallest diameter d₁, which is sizedslightly larger than the outside diameter of the catheter 120 so thatthe catheter lock 40 can slide freely along the length thereof. A distalportion 44 of the catheter lock 40 has a slightly larger diameter d₂ toallow the catheter 120 to move freely after the catheter lock 40 issecured to the boot 20. The front portion of the catheter lock has threediameter portions 46, 48 and 49, having respective diameters d₃ d₄ andd₅, designed to mate with the base portion 32 of the stem 30, andthereby providing a secondary tactile locking mechanism as will beexplained in more detail below. Also positioned in the front portion ofthe catheter lock 40 are slits 50 positioned on opposite sides thereofto facilitate the movement of the diameter portion 49 of the catheterlock 40 over the engaging portion 33 of the stem 30 and the subsequentlocking action therebetween.

The advantage of the catheter boot and locking system as describedherein is the ease of connection in combination with the difficultdisengagement of the catheter after assembly is complete (will notdisengage at clinical loads/extensions). With reference to FIGS. 3 and4, a catheter connection in a preferred embodiment will be described.After the catheter 120 has been established within the body, for examplehaving an end established in the spine as described above, and istunneled or otherwise delivered to the location of the pump or port, thecatheter connection thereto takes place. As mentioned, the catheter lock40 is configured to slide freely along the catheter 120 and thereforecan be threaded onto the end of the catheter 120 quite easily just priorto connection to the boot 20.

The lumen 122 of the catheter 120 is first slid onto the tip portion 34of the stem 30 until the catheter 120 is midway along the section 37.The catheter lock 40 is then slid onto the stem 30 and pressed in adirection toward the boot 20 until an audible clicking sound is heardand a positive connection is felt. The slits 50 enable the catheter lock40 to flex outward slightly when pressed over the engaging portion 33 tofacilitate the connection. After connection has been established betweenthe catheter lock 40 and the stem 30, the forward portion 36, having adiameter substantially equal to d₃ is within portion 46 and the engagingportion 33, having its largest diameter substantially equal to d₄ iswithin portion 48. Because portion 49 has a diameter d₅ slightly smallerthan that of the largest diameter of the engaging portion 33, once aconnection has been established, the catheter lock cannot be pulled offof the stem 30. Portion 42, having diameter d₁, is superimposed over thecatheter on section 37 of the stem 30, preventing movement of thecatheter within the lock due to the compression applied thereon andproviding a primary obstacle for removal of the catheter 120 from thestem 30. In addition, this arrangement acts to seal the connectionagainst fluid leakages between the various interfaces. Portion 49 withdiameter d₅ provides a secondary obstacle by preventing movement of thecatheter lock in a direction away from the boot.

The inventive catheter lock can be used in conjunction with variouspumps and ports as mentioned, as well as with a host of differentcatheters and catheter systems. Examples of intended uses for thecatheter system described herein is to deliver pain medicating drug(s)to a patient at locations in the body including the intrathecal space,the epidural space, arterial and venous areas and directly into tissue.A preferred embodiment of the catheter system of the present inventioncan be seen in FIGS. 6-10.

Referring to FIG. 6, a catheter system 110 has a flushing hub 140 forflushing a catheter 120 during placement thereof in a patient's body,including a main hub body 154. At a proximal end of the flushing hub140, an opening 158 provides access to an inner lumen 152 (see FIG. 9).At a distal end of the flushing hub 140, a cannula 156 extends therefromand is in communication with the inner lumen 152. The cannula 156surrounds a stylet 160, which can be seen in phantom within the catheter120, and which is attached to the main hub body 154. The relationbetween the stylet 160 and the cannula 156 and main hub body 154 can bebetter seen in FIGS. 7 and 8.

FIG. 8 shows the flushing hub 140 and stylet 160 along the length of thecatheter 120. The flushing hub 140 allows catheter flushing withoutremoval of the stylet 160 as well as the withdrawal of bodily fluid toconfirm catheter location. The stylet 160 provides internal rigidity tothe catheter 120 and allows for maneuverability via torque transmissiondown the stylet 160 from the proximal end of the catheter system 100 tofacilitate precise placement of the tip. In the preferred embodiment,the stylet 160 is coated with a hydrophillic coating for ease of removalfrom the catheter 120. The coating reduces catheter bunching that cancompromise the physical properties of the catheter 120 by leading todestructive forces on the catheter 120. The coating further reducestraction internal to the catheter 120 during stylet withdrawal andreduces the potential of tip and/or catheter malposition.

The catheter 120 is closely fitted over the cannula 156 to provide acontinuous pathway from the inner lumen 152 of the flushing hub 140 intothe lumen 122 of the catheter 120, thereby allowing for the flushing offluid from the cannula 156 through the lumen of the catheter 120 aroundthe stylet 160 to wet the stylet surface before exiting from the holes126 at the distal end of the catheter 120 (see FIG. 10).

FIG. 9 shows a cross-sectional view of the flushing hub 140. From thisview, the inner lumen 152 of the main hub body 154 can be seen, withopening 158 at the proximal end thereof. In this particular embodiment,the stylet 160 is shown affixed to the body 154 and extends through theinner lumen 152, leaving a channel 153 on either side of the stylet 160for fluid flow. Of course, the stylet 160 could be affixed in otherlocations not directly within the center of the inner lumen 152 of themain hub body 154. Also, the inner lumen 152 could be differentlyconfigured, depending on the features desired in a given cathetersystem.

Turning now to FIG. 10, a cut-away view of a distal end of the catheter120 is shown. In the preferred embodiment, catheter 120 has a lumen 122and walls 124 made of high durometer silicone for kink resistance andits beneficial properties with regard to biocompatibility andbiodurability, though other materials are certainly possible that wouldsimilarly afford the advantages of the preferred material, such aspolyethylene and polyurethane. The walls 124 in the preferred embodimentare relatively thick to further the goal of kink resistance, togethercomprising approximately half of the external diameter of the catheter(i.e., if the catheter 120 had an outside diameter of nominally 0.055inches, each wall 124 in cross-section would have a thickness of atleast 0.014 inches). At the distal end of the catheter 120, a tip 130 isrounded in the form of a bullet and made of a highly radiopaque materialto provide a dual advantage of a geometry that is less traumatic tobodily tissues and anatomical structures and an enhanced visibility,which facilitates location determination during and after introductionto the patient's body. The radiopaque material utilized for the tip 130in a preferred embodiment is a combination of cured liquid silicone andtungsten powder in approximately 50% by weight of each component.

In the walls 124 of the catheter 120, a set of side holes 126 areprovided to allow passage of fluid to and from the lumen 122. The sideholes are drilled perpendicular to the surface thereof to limit surfacearea anomalies that may result in tissue trauma and/or catheter damageupon placement. A catheter segment 128 between the tip 130 and a sidehole 126 is filled with similar material as the tip 130 to form plug132. This feature, combined with the closed-ended geometry of thecatheter 120 eliminates dead space that can host proteinaceous materialand the like, which, if present within a catheter lumen, can propogateinto an occlusion thereof.

As mentioned, one application of the present invention is for use alongwith an implantable pump to deliver medication to the intrathecal spacein a patient's spine. An indwelling catheter, such as catheter 120, isutilized to establish a fluid path from a subcutaneous pump through thedura membrane. The procedure generally consists first of embedding thecatheter in the spine (5 to 10 cm). A drop of the spinal fluid is thenallowed to form at the proximal end of the catheter 120 to confirmcatheter location, after which the catheter is clamped. A tunnel isformed from the spine to the area of the abdomen, where the pump will beimplanted, and the catheter is pulled through and cut to length. Thecatheter is then attached to the pump as described above through the useof an inventive boot and catheter lock. The pump is placed in apreviously created pocket in the area of the abdomen and the pocket isclosed. Implantation of the described system is relatively quick andeasy and provides for prolonged delivery of drugs or medication to thespine.

The present invention has been described above in terms of a presentlypreferred embodiment so that an understanding of the present inventioncan be conveyed. However, there are many alternative arrangements for acatheter system not specifically described herein but with which thepresent invention is applicable. For example, there are many differentapplications and configurations for a catheter locking system that wouldbe within the scope of the present invention and similarly, there aremany applications for a catheter and flushing system other than thosespecifically described. Although specific features have been given, thecatheter system for locking a catheter to an implantable pump and foreffectively flushing a catheter after implantation within a body of thepresent invention would equally be embodied by other configurations notspecifically recited herein. The scope of the present invention shouldtherefore not be limited by the embodiments illustrated, but rather itshould be understood that the present invention has wide applicabilitywith respect to catheter systems generally. All modifications,variations, or equivalent elements and implementations that are withinthe scope of the appended claims should therefore be considered withinthe scope of the invention.

The present invention has been described above in terms of a presentlypreferred embodiment so that an understanding of the present inventioncan be conveyed. However, there are many alternative arrangements for acatheter system not specifically described herein but with which thepresent invention is applicable. For example, there are many differentapplications and configurations for a catheter locking system that wouldbe within the scope of the present invention and similarly, there aremany applications for a catheter and flushing system other than thosespecifically described. Although specific features have been given, thecatheter system for locking a catheter to an implantable pump and foreffectively flushing a catheter after implantation within a body of thepresent invention would equally be embodied by other configurations notspecifically recited herein. The scope of the present invention shouldtherefore not be limited by the embodiments illustrated, but rather itshould be understood that the present invention has wide applicabilitywith respect to catheter systems generally. All modifications,variations, or equivalent elements and implementations that are withinthe scope of the appended claims should therefore be considered withinthe scope of the invention.

1. A coupling device for attachment of an implantable port or pump to acatheter, comprising: an arm portion having a proximal end that isfixedly attached to said port or pump and a distal end, said arm portioncomprising a flexible material and shaped substantially similar to anouter contour of said implantable port or pump, said arm portion beingbiased to a resting position in close proximity to said port or pump,wherein said arm portion is movable to a connecting position away fromsaid port or pump, and wherein said arm portion retracts to said restingposition upon release from said connecting position; and a stempositioned at a distal end of said arm portion.